Abstract

The Common Alerting Protocol (CAP) is an XML document format for exchanging emergency
alerts and public warnings. Different organizations issue alerts for specific geographic
regions. The Location-to-Service Translation (LoST) protocol provides a way to discover
servers that distribute these alerts for a geographical region. This document defines the
Service Uniform Resource Names (URN)s for warnings in the same way as they have been defined
with RFC 5031 for citizen-to-authority emergency services. Additionally, this document
suggests to use LoST for the discovery of servers distributing alerts.

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1.
Introduction

The Common Alerting Protocol (CAP) is an XML document format for exchanging emergency
alerts and public warnings. Different organizations issue alerts for specific geographical
regions. The Location-to-Service Translation (LoST) protocol provides a way to discover
servers that distribute these alerts for a geographical region. This document defines the
Service Uniform Resource Names (URN)s for warnings in the same way as they have been defined
with RFC 5031 for citizen-to-authority emergency services. Additionally, this document
suggests to use LoST for the discovery of servers distributing alerts.

4.
Examples

Figure 1 (A <findService> geodetic query) shows a regular LoST query including geodetic location
information with the Service URN pointing to 'urn:service:warning'. The semantic of the
query is: "I am at location (point,"37.775 -122.422"). Please give me a URI where I can
obtain information for warnings under the category 'urn:service:warning'.

In response to the query in Figure 1 (A <findService> geodetic query) the LoST server returns a regular
LoST response, as shown in Figure 2 (A <findServiceResponse> geodetic answer). The returned mapping information
indicates that the URIs (sip:alerts@example.com and xmpp:alerts@example.com) can be
contacted to subscribe to warning events. The service boundary indicates that subsequent
requests to the same service will lead to the same response for the geodetic region
indicated by the polygon in the <serviceBoundary> element.

The 'warning' service type describes services providing public safety alerts, i.e.,
alerts that can warn members of the public about dangers to life, health and property.
Additional sub-services can be added after expert review and must be of general public
interest and have a similar emergency nature. The expert is designated by the ECRIT
working group, its successor, or, in their absence, the IESG. The expert review should
only approve early warning based emergency services that are offered widely and in
different countries, with approximately the same caller expectation in terms of services
rendered. The 'warning' service is not meant to be used by non-emergency services related
information.